Sewing-machine tension



(Model.)

G. H. DIMOND.

SBWING'MAUHINE TENSION. f No. 324,755. Patented Aug. 18, 1885.

SEWING-MACHINE TENSlON.v

SPECIFICATION forming part of Letters Patent No. 324,755, dated August 18, 1885.

Application filed April 2T, 1885.

To @ZZ whom it may concern:

Be it known that I, GEORGE H. D1MoND,a citizen of the United States, residing` at Bridgeport, in the county of Fairiield and State of Connecticut, have invented certain new and useful Improvements in Sewing-Machine Terr sions; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention has especial relation to that class of Vheelcr & Vilson machines in which the under thread is carried by a bobbin within a bobbin-case, and the tension for the under thread is secured by passing the thread under a curved spring, the thread being pressed between the spring and the bobbin-case. An illustration of this class of tension may be found in patent to Bailey and Hurd, dated October 23, 1883. The object of my invention is to improve the construction therein shown and described.

Turning now to the accompanying drawings,for1ning part of this specification, Figure l is aback View of the bobbin-case, a portion being broken away to show the edge of the bobbin and the end of theV tension spring; Fig. 2, a front View of the bobbin-case with the bobbin removed, Fig. 3, a section of the bobbin-case on the liuc x x in Fig. 6, showing the direction in which the thread passes out from the case, the bobbin being in elevation and the parts in the same position as in Fig. I; Fig. 4t, a section of the bobbin-case on the line y y in Fig. 1,lool ing toward the top; Fig. 5, an edge View of the case with the tensionspring removed; and Fig. 6 is a similar view with the spring and bobbin in place. r

Similar letters indicate like parts in all the figures.

A indicates the bobbin-case, B the bobbin, and C the tension-spring.

D and E (see Fig. 5) arescrew-holes, which will be again referred to.

F is a diagonal slot extending through the edge of the case, and G is a recess extending from the front and intersecting said slot, through which the thread may be passed either before or after the bobbin is placed in the case.

H is a hole or aperture in the case, into which the end ot' the tensionspring passes.

(Medel.)

The tension-spring may be attached outside or inside the case. I preferably, however, attach it upon the outside, as shown, and provide for that purpose a recess, K, so that the spring at the front shall not project beyond the edge of the case. The spring is preferably attached to the case by a screw, L, which engages hole D. As indicated in Fig. 3, the spring is curved outward slightly from the case, so that its normal position is notin contact 'therewith between slot F and hole I-I. The object of this construction is to enable me to regulate the tension to suit all classes of thread, which I accomplish perfectly by'means of a screw, M, which passes through the spring and engages hole E in the case, thus controlling the pressure upon the thread as it passes between the spring and the case. The end of the spring is bifurcated, forming two prongs, N and O, with a thread hole, I), at the base of the prongs. Prong N (the one toward the front of the case) is longest, and its end is curved downward just sufiicientlyto pass into hole H and under an overhanging portion or flange, Q, against which it bears, so that it is impossible for the end of the spring to be lifted away from the bobbincase should there be a knot in the thread, or should it become tangled in any manner. My present construction renders it impossible for the end of the spring to become bent out of place, or to interfere in any manner with the working of the hook or the needle. The shorter prong O conforms substantially with the general curvature ofthe spring, the end being bent slightly downward to prevent unthreading.

It will be noticed in Fig. I that, as seen from the back, there is ample space between the metal ofthe case and the spring to permitthe thread to pass in freely. rllhe course of the thread is indicated by the line R in Fig. 3.

In threading u p, the bobbin is put in from the front, and, in the position of the case in Fig. 2, would turn from left to right in unwinding. rIhe end of the thread is passed through the case, entering atrecess G and passing out at the end of slot F, as seen in Fig. 6. It is then drawn toward the right, as seen in Figs. 1 and 6, and passes under the spring and into the thread-hole between the prongs at its free end.

IOO

A s stated above, the pressure of the .sp-ring thread passes to the upon the thread may screw M either in or Having thus claiml. A bobbin case for rotating-hook sewingmachines, having a slot through which the outside, and a hole or aperture, H, with an overhanging flange, in combination with aspringsecured to said case, and bifureated at its end to form prongs, between which the thread passes, the front prong being made longest and curved downward under the flange to hold the spring in place, and a tensionscrew to regulate the pressure upon the thread.

2. A bobbilrease for rotating-hook sewingmaehin s havingadiagonal threadslot,F,and a hole or aperture, H, with an overhanging flange, in combination with va spring, one end of vwhich is attached to the case, is then curved outward slightly therefrom, then inward again against the ease, and at its free end is provided with prongs, the front prong being curved under the flange.

3. The combination, in arotating-hook sewl be regulated by turning out, as may be required described my invention, I

ing-machine, with a bobbincase having a diagonal threadfslot anda hole or aperture, H, with an overhanging flange, of a curved tension-spring which does not wholly cover the thread-slot, and has at its free end prongs, between which the thread is delivered, one of which is curved downward under the ange, as and for the purpose set forth.

4. In a rotatinghook sewing-machine, the combination, with a bobbincase having a thread-slot and a hole or recess, H, with an overhanging iiange, of a tension-spring attaehed thereto, having at its free end'prongs, between which the thread passes, the front prong being curved downward under the Hange to hold the spring in place, the back'prong following the curve of the spring, so that the thread cannot escape, but in threading up may be readily drawn under it.

, In testimony whereof I affix my signature in presence of two witnesses.

GEORGE H. DIMOND.

Witnesses:

A. M. WoosTnR, A. B. FAIRcHILD. 

